In plating copper electrolessly, the prior art processes have all substantially conducted the plating operation on an alkaline pH side of the pH scale such as above pH 8 and above employing generally the --OH (hydroxide) radical supplied by sodium hydroxide, potassium hydroxide, or various other alkaline agents, such as sodium carbonates, ammonium, etc. However, it is well known, the high temperature substrates which are finding increasing application as replacements for metal substrates in flexible, flat circuitry are especially susceptible to an alkaline attack. For example, the polyimides which will be further disclosed herein are susceptible to an alkaline attack and many electroless copper deposition processes are not suitable with polyimide substrates because these processes are invariably carried out in an alkaline medium.
Other substrates previously mentioned above are equally susceptible to the alkaline or alkali attack and, therefore, a viable and efficient acid bath from which copper can be plated electrolessly has been a desideratum in the art.